WDPN32 PGTW 271500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 09W (SAOLA) WARNING NR 016//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 16.2N 123.2E
   INITIAL INTENSITY: 125 KTS
   GEOGRAPHIC REFERENCE: 159 NM NORTHEAST OF MANILA, PHILIPPINES
   MOVEMENT PAST 6 HOURS: SOUTHEASTWARD AT 04 KTS
   SIGNIFICANT WAVE HEIGHT: 50 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS A
MEDIUM-SIZED, HIGHLY-SYMMETRICAL SYSTEM THAT HAS FURTHER DEEPENED
AROUND THE EYEWALL AS IT MAINTAINED A 17-NM, SHARPLY OUTLINED EYE
THAT WAS CONCENTRIC WITH A DEFINED CIRCULATION ON A COMPOSITE
WEATHER RADAR LOOP. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON THE EYE. THE INITIAL INTENSITY OF 125KTS IS 
ASSESSED WITH HIGH CONFIDENCE BASED ON OVERALL ASSESSMENT OF AGENCY 
AND AUTOMATED DVORAK ESTIMATES AND REFLECTS THE IMPROVED CONVECTIVE 
STRUCTURE. ANALYSIS INDICATES A FAVORABLE ENVIRONMENT WITH VERY WARM 
SST IN THE PHILIPPINE SEA, LOW VWS, AND MODERATE RADIAL OUTFLOW ALOFT,
OFFSET ONLY BY LOCALIZED OCEAN UPWELLING.

INITIAL WIND RADII BASIS: PERSISTENCE.

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE WEST AND
NEAR EQUATORIAL RIDGE (NER) TO THE SOUTH.


AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.5 - 127 KTS
   RJTD: T6.5 - 127 KTS
   CIMSS ADT: 104 KTS AT 271130Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: MODERATE RADIAL

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   INITIAL WIND RADII: MEDIUM

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TY SAOLA WILL BEGIN TO SLOWLY TRACK
EAST-NORTHEASTWARD AS THE NER TO THE SOUTH ASSUMES STEERING. AFTER TAU 
12, A NORTH-SOUTH EXTENSION OF A SECONDARY DEEP-LAYER STR TO THE 
NORTHEAST WILL ASSUME STEERING AND DRIVE THE SYSTEM NORTHWARD, THEN 
AFTER TAU 24, THIS SAME STR WILL BUILD AND SPEED UP THE SYSTEM 
NORTHWESTWARD TOWARD TAIWAN VIA THE LUZON STRAIT. THE FAVORABLE 
ENVIRONMENT, TEMPERED BY LOCALIZED OCEAN UPWELLING, WILL BECOME 
MARGINAL WITH THE ONSET OF DRY AIR INTRUSION IN THE LOW LEVELS AND 
WILL SLIGHTLY WEAKEN THE SYSTEM TO 120KTS AT TAUS 12-24. AFTERWARD, AS 
THE CYCLONE SPEEDS NORTHWESTWARD, OCEAN UPWELLING AND DRY AIR 
INTRUSION WILL DIMINISH AND FUEL A SECONDARY INTENSIFICATION TO A PEAK 
OF 135KTS AROUND TAU 48. AFTER TAU 48, INCREASING VWS AND LAND 
INTERACTION WILL GRADUALLY WEAKEN THE SYSTEM DOWN TO 70KTS BY TAU 120 
AFTER IT CROSSES THE TAIWAN STRAIT AND MAKES LANDFALL OVER EASTERN 
CHINA NORTHEAST OF HONG KONG. 

MODEL DISCUSSION: NUMERICAL MODELS ARE IN OVERALL GOOD AGREEMENT
WITH THIS LOOPING TRACK FORECAST WITH A GRADUAL SPREAD TO JUST 82NM
AT TAU 72 THEN TO 318NM AT TAU 120, SANS NAVGEM, THE EXTREME
LEFT-OF-TRACK OUTLIER. THERE IS OVERALL MEDIUM CONFIDENCE IN THE
JTWC TRACK FORECAST THAT IS LAID JUST TO THE RIGHT OF CONSENSUS TO
OFFSET NAVGEM.  

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   TRACK 72-120 HR: MEDIUM
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: LOW//
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